/**
 * $RCSfile$
 * $Revision$
 * $Date$
 *
 * Copyright 2003-2007 Jive Software.
 *
 * All rights reserved. Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.jivesoftware.smack;

import org.jivesoftware.smack.packet.Message;

import java.util.Set;
import java.util.Collection;
import java.util.Collections;
import java.util.concurrent.CopyOnWriteArraySet;

/**
 * A chat is a series of messages sent between two users. Each chat has a unique
 * thread ID, which is used to track which messages are part of a particular
 * conversation. Some messages are sent without a thread ID, and some clients
 * don't send thread IDs at all. Therefore, if a message without a thread ID
 * arrives it is routed to the most recently created Chat with the message
 * sender.
 * 
 * @author Matt Tucker
 */
public class Chat {

	private ChatManager chatManager;
	private String threadID;
	private String participant;
	private final Set<MessageListener> listeners = new CopyOnWriteArraySet<MessageListener>();
	private boolean isShutdown = false;

	/**
	 * Creates a new chat with the specified user and thread ID.
	 * 
	 * @param chatManager
	 *            the chatManager the chat will use.
	 * @param participant
	 *            the user to chat with.
	 * @param threadID
	 *            the thread ID to use.
	 */
	Chat(ChatManager chatManager, String participant, String threadID) {
		this.chatManager = chatManager;
		this.participant = participant;
		this.threadID = threadID;
	}

	/**
	 * Returns the thread id associated with this chat, which corresponds to the
	 * <tt>thread</tt> field of XMPP messages. This method may return
	 * <tt>null</tt> if there is no thread ID is associated with this Chat.
	 * 
	 * @return the thread ID of this chat.
	 */
	public String getThreadID() {
		return threadID;
	}

	/**
	 * Returns the name of the user the chat is with.
	 * 
	 * @return the name of the user the chat is occuring with.
	 */
	public String getParticipant() {
		return participant;
	}

	public void shutdown() {
		isShutdown = true;
	}

	/**
	 * Sends the specified text as a message to the other chat participant. This
	 * is a convenience method for:
	 * 
	 * <pre>
	 * Message message = chat.createMessage();
	 * message.setBody(messageText);
	 * chat.sendMessage(message);
	 * </pre>
	 * 
	 * @param text
	 *            the text to send.
	 * @throws XMPPException
	 *             if sending the message fails.
	 */
	public void sendMessage(String text) throws XMPPException {
		Message message = new Message(participant, Message.Type.chat);
		message.setThread(threadID);
		message.setBody(text);
		chatManager.sendMessage(this, message);
	}

	/**
	 * Sends a message to the other chat participant. The thread ID, recipient,
	 * and message type of the message will automatically set to those of this
	 * chat.
	 * 
	 * @param message
	 *            the message to send.
	 * @throws XMPPException
	 *             if an error occurs sending the message.
	 */
	public void sendMessage(Message message) throws XMPPException {
		// Force the recipient, message type, and thread ID since the user
		// elected
		// to send the message through this chat object.
		message.setTo(participant);
		message.setType(Message.Type.chat);
		message.setThread(threadID);
		chatManager.sendMessage(this, message);
	}

	/**
	 * Adds a packet listener that will be notified of any new messages in the
	 * chat.
	 * 
	 * @param listener
	 *            a packet listener.
	 */
	public void addMessageListener(MessageListener listener) {
		if (listener == null) {
			return;
		}
		// TODO these references should be weak.
		listeners.add(listener);
	}

	public void removeMessageListener(MessageListener listener) {
		listeners.remove(listener);
	}

	/**
	 * Returns an unmodifiable collection of all of the listeners registered
	 * with this chat.
	 * 
	 * @return an unmodifiable collection of all of the listeners registered
	 *         with this chat.
	 */
	public Collection<MessageListener> getListeners() {
		return Collections.unmodifiableCollection(listeners);
	}

	/**
	 * Creates a {@link org.jivesoftware.smack.PacketCollector} which will
	 * accumulate the Messages for this chat. Always cancel PacketCollectors
	 * when finished with them as they will accumulate messages indefinitely.
	 * 
	 * @return the PacketCollector which returns Messages for this chat.
	 */
	public PacketCollector createCollector() {
		return chatManager.createPacketCollector(this);
	}

	/**
	 * Delivers a message directly to this chat, which will add the message to
	 * the collector and deliver it to all listeners registered with the Chat.
	 * This is used by the Connection class to deliver messages without a thread
	 * ID.
	 * 
	 * @param message
	 *            the message.
	 */
	void deliver(Message message) {
		// Because the collector and listeners are expecting a thread ID with
		// a specific value, set the thread ID on the message even though it
		// probably never had one.
		if (isShutdown)
			return;

		message.setThread(threadID);

		for (MessageListener listener : listeners) {
			listener.processMessage(this, message);
		}
	}

	@Override
	public boolean equals(Object obj) {
		return obj instanceof Chat
				&& threadID.equals(((Chat) obj).getThreadID())
				&& participant.equals(((Chat) obj).getParticipant());
	}
}